This invention relates to a composite cover plate for a compartment of electric components, especially for the metallic compartment of an electric condenser that is open on one side.
Cover plates for locking the compartment of an electric condenser are, for the most part, manufactured from artificial material in combination with rubber-elastic sealing elements. Such cover plates, however, can only be employed for temperatures up to 100.degree. C. since the artificial material of the cover plate will become too soft at higher temperatures and then no longer have sufficient resistance to deformation. Moreover, the permeation consistency of the artificial cover is rapidly reduced at higher temperatures when gases or fluids are involved.
Such problems do not exist in cover plates which consist mainly of aluminum in association with rubber-elastic sealing elements. In such aluminum cover plates, however, problems arise in regard to electric insulation, this problem arising not only in regard to electric insulation as concerns the metallic cup compartment of the condenser but also as concerns electric extension working. By contrast, such electrical insulation problems do not arise for plates of artificial material.
In view of this situation, there have been made known a variety of cover plates consisting of a combination of rubber, artificial material and aluminum. None of the heretofore cover plates, however, solved in a satisfactory way the requirements expected from such cover plates.
In a not yet published application (PCT/EP No. 81/00011), there has been described a composite cover plate for the compartment of an electric component, especially for the metallic cup compartment of an electric condenser which is open on one side. One surface of this cover plate is, in substance, completely coated with rubber on one side as well on its outer edge, the opposite surface being coated with rubber in the edge or border area, e.g. the cover plate consisting overall of a rubberized aluminum disc and an artificial material disc and having tight electrical insulation resistant to the permeation of gas and fluids which can withstand elevated tension. The lead-through element extending into the inner area of the condenser is of one-piece and formed from the aluminum disc. The disc of artificial material lies on the rubberized surface of the aluminum disc. The surface of the aluminum disc which is rubberized only on the outer edges remains free to establish external connections. By a reinforcement formed on the lead-through element which acts as a locking element, the rubberized aluminum disc and the disc of artificial material form a strong composite, i.e. the compound cover plate, and are forced against each other in the direction of their normal area.
With this formation however, there is not solved the problem of how the plate may be provided with several electric lead-through element insulated against each other. Moreover, even the providing of safeguards in this plate against overloads is not entirely without problems.